This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. xc2xa7119 from my application entitled BUBBLE-JET TYPE INK-JET PRINTHEAD filed with the Korean Industrial Property Office on Jul. 24, 2000 and there duly assigned Serial No. 2000/42365.
1. Field of the Invention
The present invention relates to an ink-jet printhead, and more particularly, to a bubble-jet type ink-jet printhead.
2. Description of the Related Art
The ink ejection mechanisms of an ink-jet printer are largely categorized into two types: an electro-thermal transducer type (bubble-jet type) in which a heat source is employed to form a bubble in ink causing ink droplets to be ejected, and an electro-mechanical transducer type in which a piezoelectric crystal bends to change the volume of ink causing ink droplets to be expelled.
Meanwhile, a bubble-jet type ink-jet printhead having an ink ejector needs to meet the following conditions. First, a simplified manufacturing process, the low manufacturing cost, and high volume production must be allowed. Second, to produce high quality color images, creation of small and minute satellite droplets that trail ejected main droplets must be prevented. Third, when ink is ejected from one nozzle or ink refills an ink chamber after ink ejection, cross-talk with adjacent nozzles from which no ink is ejected must be prevented. Fourth, for a high speed print, a cycle beginning with ink ejection and ending with ink refill must be as short as possible.
However, the above conditions tend to conflict with one another, and furthermore, the performance of an ink-jet printhead is closely related to the structures of an ink chamber, an ink channel, and a heater, the type of formation and expansion of bubbles associated therewith, and the relative size of each component.
In efforts to overcome problems related to the above requirements, ink-jet print heads having a variety of structures have been proposed in U.S. Pat. Nos. 4,339,762; 4,882,595; 5,760,804; 4,847,630; and 5,850,241, European Patent No. 317,171, and Fan-Gang Tseng, Chang-Jin Kim, and Chih-Ming Ho, xe2x80x9cA Novel Micoinjector with Virtual Chamber Neckxe2x80x9d, IEEE MEMS ""98, pp. 57-62. However, ink-jet printheads proposed in the above patents and literature may only satisfy some of the aforementioned requirements but do not completely provide an improved ink-jet printing approach.
To solve the above problems, it is an objective of the present invention to provide a bubble-jet type ink-jet printhead having a structure for effectively preventing a back flow of ink.
It is another objective of the present invention to provide a bubble-jet type ink-jet printhead in which an ink channel, along which ink flows, has a simple structure and ink is supplied smoothly.
It is still another objective of the present invention to provide a bubble-jet type ink-jet printhead that allows for minute adjustment in an ink ejection amount and ejection of a fixed amount.
It is yet still another objective of the present invention to provide a bubble-jet type ink-jet printhead that allows for high-speed operation by shortening an ink refill time.
It is further an object of the present invention to provide an ink jet printhead that produces uniform droplet size.
It is still further an object of the present invention to provide an ink jet ejection mechanism that has two heater units for each nozzle hole;
It is also an object of the present invention to provide an ink chamber that can be filled from two directions.
Accordingly, to achieve the above objectives, the present invention provides a bubble-jet type ink jet printhead including a substrate, a plurality of chamber walls arranged parallel to one another on the substrate for dividing a chamber into a plurality of unit chambers having a predetermined height, which are ink flow areas, a bubble generating means, provided for each unit chamber, which includes two unit heaters spaced apart by a predetermined distance on the substrate, and a nozzle plate, combined above the substrate, in which a plurality of nozzles are formed, each nozzle corresponding to a region between the two unit heaters of each bubble generating means. In the ink-jet printhead, ink is supplied from both sides of the unit chamber.
Furthermore, the two unit heaters of each bubble generating means are electrically coupled to each other. The two unit heaters may be integrated or spaced apart by a predetermined distance, between which an electrical connection member is disposed.
The opposite portions of the two unit heaters of the bubble generating means may be coupled to a common signal line and the exterior ends of the two unit heaters may be commonly coupled to one parallel connection member. Alternatively, the ends of one side of each bubble generating means are coupled to a serial connection member while the ends of the other side are coupled to electrical signal lines, respectively. The exterior ends of the two unit heaters of the bubble generating means may be connected to the parallel connection member integrated therewith, and the common signal line may be commonly coupled to the middle portions of a plurality of bubble generating means.
A first insulating layer may be disposed between the common signal line and the bubble generating means, and a contact hole for contacting the common signal line and a connection portion of both unit heaters of the bubble generating means may be formed in the first insulating layer. A second insulating layer may be formed on the uppermost surface of a stack structure including the bubble generating means and the chamber wall is formed on the second insulating layer.